The present project proposal, which is divided into two sub-projects focus on the study of the sandfly biological aspects related with its vector potential, and control strategies to decrease leishmaniasis transmission. Sandfly control with residual insecticides, sprayed at the peri and intradomicile level (DDT, Malathion), combined with curtain impregnations (pyrethroides) are proposed for diminishing sandfly populations in endemic foci where transmission is taking place at those levels. Two areas typical of tegumentary and visceral leishmanaisis were selected for the field trials, in which insecticides will be applied on the basis of previous laboratory testing of the compound with colonized sandflies. Evaluation will rely on phlebotomine collections throughout the year as compared with control, untreated. The capacity of Colombia sandflies to transmit Leishmania from different species and subspecies, either in single or mixed infections will be evaluated through artificial infections with promastigotes or amastigotes. Infective potentia will be assessed by evaluating the infection rate, pattern of development, and morphology. Infectivity of egested parasites via forced-feeding and through bite will also be determined. Capacity to harbor and transmit mixed L. braziliensis -L. panamensis infection and L. panamensis - L. chagasi will be explored with similar methodologies.